2 Types of Bones

-Blood vessels and osteoblasts

-Compact Bone: Very loosely packed apatite crystals w/ collagen fibres arranged in sheets of lamellae-Spongy Bone: collagen fibres arranged in all directions; less dense network of apatite crystals -struts can tell you forces that are acting upon the bone

*Periosteum (outside of bone) is where bone forms - osteoblasts gradually enclose blood vessel and fill to enclose it

Features of Bones

-Forces acting on bones and bodies -how it affects bones

Forces: Compression, tension, shear and torsion act on bodies and bones -The architecture of bone is dictated by the stresses acting upon it

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Assymetric Load -> best shape

Best shape when only one plane

-For Assymetric Load: Cyclinder is a robust geometric form that can deal with both tension and compression -Only one plane: When bone primarily resists bending in only one plane, cylinder is NOT most efficient shape (joists, I-beams)

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Joints

-3 types and amount of mobility

-Features most mobile joints have to reduce friction and to maintain congruence

-Skeletal muscles composed of Muscle fibres (that are bundled in muscle fasicles) -contain many internal myofibrils-Myofibrils: formed from a chain of repeating units called sacromeres (striations) -each has thin filaments (actin) and thick filaments (myosin)-Sacrolemma: External membrane of muscle cells

Muscles -> how they work

Force versus Speed

-effect of length and width of muscles

-Forces versus Speed-each sacromere contracts at the same rate -> long muscles shorten faster and further than short ones-Each sacromeres contracts with the same force, thick muscles are more powerful than thin ones

Muscle Metabolism

-types of fuels used

-Type of fuel used changes in response to activity level-Metabolic transitions are controlled by hormones -affect production and release from storage tissues -affect ability of muscles to use the fuels-Steady-state activity: utilize which fuel is abundant

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Main energy source used in low to moderate activity and Sustained activity

-how regulated

-Low to moderate activity -glucose is main fuel -controlled by insulin and cortisol -> promote liver glycogen breakdown -enhance glucose uptake by the muscle-Sustained activity -triglycerides become increasingly important -controlled by lipase which is controlled by corticotropin, epinephrin, norepinephrin and glucagon -mobilized from muscle and adipose tissues

-Capillary Tortuousity: Capillaries weaves back and forth across the muscle -O2 levels decline along capillary - region of muscle may be served by many capillaries

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Cursorial Advantage (animals adapted to running far and over landscapes)

-Forage over large arias-Seek new food sources-Seasonal variation in food

*important for both predators and prey

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Elastic Storage of energy

-benefits

-Skeletons can store elastic energy -Potential mechanical energy stored-occurs through stretching of CT-When muscles contract, it stretches the CT and bends the bones -when relaxes, energy can be released to help in locomotion -recoil in spider's legs can help decrease energy

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Moving in the Environment

-2 main environmental factors

-2 main enviro factors; -Gravity -Fluid properties (also important for flying animals)*physiology of locomotion has more to do with the physical environment than the pattern of limb movement

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Which forces affect terrestrial animals most

-How aquatic animals deal with this force

-Gravity affects terrestrial animals more than aquatic -have complex and substantial musculature to compensate-Aquatic animals benefit from body density that equals that of enviro (buoyancy is the tendency to oppose gravity - upwards force)

Buoyancy

e.g. shark

-Sharks produce lots of triglyercides in liver and cartilage skeleton -> help buoyancy

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Fluid Mechanics

-fluid dynamics

-Boundary Layer

-moving through fluid = complex pattern of flow-Fluid dynamics: rules that describe the movement of a fluid (also applies to air)-Boundary Layer: Molecular layer of fluid that is influence by the surface of the object - thickness of this layer is dependent on the fluid viscosity

Reducing Drag

-What swimmers and fliers have to overcome (3)

-For an object to move it must overcome drag -does this by streamlining

-Reduce drag-Generate lift-Generating thrust

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How Birds generate lift

-How shape and angle of attack affect lift (2)

-wings rounder at frong, curved on top and tapers towards back-generates a pressure difference-get pocket of negative pressure behind back = upwards lift-longer curved surface means greater lift but also greater drag-high angle of attack also increases lift -but also need greater velocity to get going

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Generating lift (2)

-soaring

-Aspect Ratio

-Gliding: no metabolic cost - only maintained over short distances but gradually descent towards the ground-True flight: remain airborne for long periods -Soaring: using lift from natural air currents to overcome gravity

Cost of Transport for different types of animals

-Land: must fight effects of gravity (highest COT)-Air: lift minimizes the effect of gravity-Swimmers: neutral buoyancy negates the effects of gravity - have the lowest cost of tranport due to buoyancy

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Costs of locomotion; Effects of body size

-absolute and relative

-Relative; in water and land/air

-Larger animals use more energy to move because they are larger (in absolute terms)-In proportion to body mass, small animals use more energy to move a given distance -locomotion is more economical for large animals than small animals-Smaller animals in water use more energy because; -drag increases with surface area - but power increases with muscle mass (MORE SO)-Land/Air: -smaller animals need more uneconomical fast-twitch fibres to move appendages faster -larger animals can store more elastic energy during movement -larger muscles and tendons store more elastic energy